Cancer patients can experience a wide range of psychological difficulties. Social support, particularly support provided by spouses, can play a critical role in helping a person cope successfully with the ongoing demands of cancer. However, recent criticisms of the social support literature have argued that understanding how support operates is important. Global theories of the relationship between support and psychological outcomes have been investigated (e.g., support as a stress buffer), with little attention given to the psychological factors that influence the type of support people prefer, the psychological factors that influence the type of support people provide, and how support interactions operate to influence well-being. The primary goal of the proposed research is to closely examine support-related interactions of cancer patients and their partners. Specifically, this study will address three issues. First, the psychological characteristics of support providers (spouses) and recipients (cancer patients) that determine what type of support is provided and preferred will be investigated. Second, the study will investigate whether a match between psychological characteristics of partners in support-related interactions predicts the psychological adjustment of the support recipient. Third, the direct and indirect effects of support upon psychological distress and well-being will be examined using a longitudinal design. The study will have a longitudinal design. Patients with either breast or gastrointestinal cancer and their healthy partners will participate in the study. Patients and partners will be recruited into the study when the patient begins outpatient chemotherapy treatment. Three times of assessment will be included, with the. third assessment scheduled six months following the initial assessment. Clinical implications of this study include identification of appropriate targets for interventions to improve the mental health of cancer patients: Is it beneficial to include spouses in psychological interventions? Should interventions encourage spouses of patients to "agree" with the patient's preferences for support and provide this support, or should interventions encourage spouses to provide support which encourages independence? The study will also advance our theoretical understanding of social support.